There could not be a more perfect illustration to the words that Prince Harry spoke at his late mother's memorial service last Friday: to him and his brother, Princess Diana was simply 'the best mother in the world'.

These remarkable and intimate photographs, two taken by Prince William and one by Prince Harry on a camera belonging to a nanny, illuminate his description: Diana is relaxed, playful and exudes a warmth that speaks of her love for her boys.

The pictures, which have never been published before, were taken during a visit to Highgrove by Diana's close friend and former flatmate Carolyn Bartholomew, and her new son Jack, in 1989.

The Princes borrowed a camera belonging to Mary Bruce, Jack's nanny, and for almost 18 years the photographs lay hidden in a box with Miss Bruce's other personal mother's house in 1989. Mary was there, and showed them to us.

'I said they would be a great memento and I would love to have them. She laughed and said, "You can have them when I'm gone - when I won't need them any more." 'And true to her word, a few months before she passed away she gave my mother the pictures to give to me.

Mary didn't have any family so I suppose her gifts had to be shared out to those in her immediate circle of friends.' Mrs Paton, 72, added: 'Mary knew how special these pictures were.

When she gave me an envelope with the pictures inside, she said, "There you are. I'm keeping my promise to Norrie."' She said Mary was very proud of the pictures but would never have taken them herself. 'She told me the boys borrowed her camera and took the photographs. It was a very nice afternoon.

'I think she'd be really happy that the pictures are being published now and I am sure they will bring as much pleasure to the public as they have brought to me and my son.'

In the first shot, which Mary told Isabella was taken by William, Diana exudes love and pride as she beams mischievously into the camera. Dressed casually in white shorts and a pink sweatshirt, she looks like any other happy mother.

In the next, apparently taken by five-year-old Harry, she is seen posing contentedly with Carolyn while William peers between the two women.

Finally we see Harry, dressed in children's military fatigues, seated next to Miss Bruce and cradling baby Jack as he smiles proudly at the camera and his older brother, who is once again behind the lens.